[PDF] Orientation Patterned Gallium Arsenide For Quasi Phasematched Infrared Nonlinear Optics eBook

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Page : 77 pages
File Size : 21,76 MB
Release : 2002
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Coherent optical sources in the mid-infrared region (mid-IR) are important fundamental tools for infrared countermeasures and battlefield remote sensing. Nonlinear optical effects can be applied to convert existing near-IR laser sources to radiate in the mid-IR. This research focused on achieving such a conversion with a quasi-phase matched optical parametric oscillators using orientation-patterned gallium arsenide (OPGaAs), a material that can be quasi-phased matched by periodically reversing the crystal structure during the epitaxial growth process. Although non-linear optical conversion was not ultimately achieved during this research, many valuable lessons were learned from working with this material. This thesis reviews the theory of nonlinear optics and explores the importance of accurate refractive index measurements to proper structure design. The details of four nonlinear optical experiments are presented recommendations are offered for the design of future OPGaAs crystals. Recommendations are also made for improved experimental techniques.

Author : Michael D. Harm
Publisher :
Page : 77 pages
File Size : 38,72 MB
Release : 2002-03-01
Category :
ISBN : 9781423506744

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Coherent optical sources in the mid-infrared region (mid-IR) are important fundamental tools for infrared countermeasures and battlefield remote sensing. Nonlinear optical effects can be applied to convert existing near-IR laser sources to radiate in the mid-IR. This research focused on achieving such a conversion with a quasi-phase matched optical parametric oscillators using orientation-patterned gallium arsenide (OPGaAs), a material that can be quasi- phased matched by periodically reversing the crystal structure during the epitaxial growth process. Although non-linear optical conversion was not ultimately achieved during this research, many valuable lessons were learned from working with this material. This thesis reviews the theory of nonlinear optics and explores the importance of accurate refractive index measurements to proper structure design. The details of four nonlinear optical experiments are presented recommendations are offered for the design of future OPGaAs crystals. Recommendations are also made for improved experimental techniques.

Author : Ryan K. Feaver
Publisher :
Page : 160 pages
File Size : 47,64 MB
Release : 2017
Category : Gallium arsenide semiconductors
ISBN :

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Optical parametric oscillators (OPOs) utilizing quasi-phase matched materials offer an appealing alternative to direct laser sources. Quasi-phase matched materials provide a useful alternative to traditional birefringent nonlinear optical materials and through material engineering, higher nonlinear coefficients can now be accessed. Orientation patterned gallium arsenide (OPGaAs) is an ideal material because of its broad IR transmission and large nonlinear coefficient. In contrast to ferroelectric materials, such as lithium niobate, where the pattern is fabricated through electric poling, zincblende materials, like OPGaAs, are grown epitaxially with the designed pattern. Generating longwave output from a much shorter pump wavelength, however, is relatively inefficiency due to the large quantum defect when compared to similar devices operating in the 3-5 μm regime. One method to increase pump to idler conversion efficiency is to recycle the undesired and higher energy signal photons into additional idler photons via a second nonlinear stage. An external amplifier stage can be utilized, where the signal and idler from the OPO are sent to a second nonlinear crystal in which the idler is amplified at the expense of the signal. Alternatively, the second crystal can be placed within the original OPO cavity where the signal from the first-stage acts as the pump for the second crystal and the resonant intensity of the signal is higher. Pumping the second crystal within the OPO should lead to higher conversion efficiency into the longwave idler. The grating period needed for the second crystal to use the signal from the first crystal to produce additional idler has the fortuitous advantage that it will not phase match to the original pump wavelength, avoiding unwanted nonlinear interactions. Therefore, a simple linear cavity can be utilized where the pump from the first-stage will simply propagate through the second crystal without undesired results. Without this feature, the pump would need to be coupled out of the cavity before it enters the second crystal. Initial numerical simulations using a custom model, implemented in MATLAB® for the proposed linear, two-stage, cascaded, OPGaAs nanosecond OPO suggest a significant improvement in conversion efficiency over a single-stage device can be obtained. The numerical model includes diffraction, crystal loss, phase mismatch, pump depletion, and back conversion, it assumes monochromatic waves and neglects group velocity dispersion. For a singly resonant oscillator (SRO) pumped by a 2.052 μm Tm:Ho,YLF laser with 45 ns pulse width, the addition of the second crystal in the cavity increases idler generation by a factor of two and exceeds the quantum defect limit. Experimentally, the cascaded OPGaAs OPO demonstrated a ~3% slope efficiency. Limited output may be the result of improper phase matching, given that two distinct idlers wavelengths were observed. Tuning the OPGaAs crystals to generate identical idlers should improve efficiency. The linewidth of the signal serving to pump the second-stage likely reduced efficiency as well. To our knowledge, this is the first cascaded OPO using OPGaAs, and the first cascaded OPO operating in the longwave infrared where the same longwave idler was generated in the both crystals.

Author : Majid Ebrahim-Zadeh
Publisher : Springer Science & Business Media
Page : 630 pages
File Size : 13,38 MB
Release : 2008-01-02
Category : Science
ISBN : 140206439X

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Covering fundamental principles and the state of the art, this is a collection of reviews from experts in mid-infrared (mid-IR) coherent sources. Among the sources covered are optical parametric oscillators, difference frequency generators, and the most recent broadband crystalline, quantum cascade, and fiber lasers. The authors show how advances in mid-IR science and technology make these sources indispensable for a variety of applications.

Author : M. M. Fejer
Publisher :
Page : 29 pages
File Size : 11,24 MB
Release : 2007
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This program focused on the development of micro-structured nonlinear optical materials and quasi- phasematched devices based on those materials. The two material systems investigated, periodically-poled ferroelectrics, especially lithium niobate (PPLN), and orientation-patterned GaAs (OP-GaAs), enable nonlinear interactions impossible in conventional nonlinear media. The work included characterization of vapor- transport-equilibrated materials, enhancements in periodic-poling technology, and development of tight bends in proton-exchanged waveguides. After the materials characterization and improvements in process development, we fabricated new devices including OP-GaAs devices for broadband optical parametric generation (OPG) at mid-infrared wavelengths, bulk PPLN devices for soliton amplifiers, and PPLN reverse- proton-exchanged waveguide devices for quasi-group-velocity-matching, telecommunication applications and generation of nearly-transform-limited OPG. Supplemental MlPR funding from DARPA was used to support and purchase ceramic fabrication equipment for the fabrication of transparent laser host materials, supported primarily under ARO Grant DAADI9-02-1-0184.

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Page : 0 pages
File Size : 34,27 MB
Release : 2000
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As described in our original proposal, the goal of this project is to create a new type of engineered nonlinear optical material, orientation-patterned GaAs, and use it to demonstrate improved high-power coherent mid-infrared sources. Considerable effort has been devoted over the past decade to the development of mid-IR coherent sources based on nonlinear optical frequency conversion, e.g., optical parametric oscillator (OPOs), pumped by available high-power near-IR sources such as diode-laser-pumped solid-state lasers or near-IR diode lasers themselves. The rapid development of quasiphasematched materials, especially periodically-poled ferroelectrics, has revolutionized this field for wavelengths in the 2-4 micrometers region. At 4 to 5 micrometers absorption limits the maximum power attainable to the range of several watts, and operation is entirely precluded in the 8 to 12 micrometers band. The orientation-patterned GaAs that we are developing is intended to complement periodically-poled ferroelectrics, providing a lithographically-engineerable low-loss material for high power devices at wavelengths beyond 4 micrometers.